This invention relates to a manual relief gas vent which can be placed in a drum lid to control the pressure in the drum.
2. Description of the Previously Published Art
Various chemical materials have been stored in sealed drums. Some of these materials will produce a gas. After a period of time a gas pressure will build up and a problem develops as to how to safely vent the gas, especially when it is an explosive gas such as hydrogen. For example, when Raney nickel is stored in a sealed drum, there is a tendency for hydrogen gas to be generated which should be vented. When the drum is opened for use, it is necessary to carefully open the drum band and slowly pry up the lid to relieve any gas pressure which may exist inside.
One solution to the problem is to use an automatic relief valve which is spring loaded. It could be set to vent the drum whenever the pressure was above a certain level such as 3 psig. There is an environmental control problem, however, with these valves because there is no way to control the gas coming off. If there are many drums in an unvented storage room on a hot day, the drums will all generate volumes of gas which the valves will automatically vent to the room. There will be no way to prevent the gas from accumulating in the room.
Gas vents have been placed in drums in the past, but these vents extend vertically to some extent such that they extend above the rim of the drum when they are inserted into the bung hole of the drum lid. When the valves extend above the drums, it is not possible to stack the drums one on top of the other.
In U.S. Pat. No. 4,688,591, a relief valve is used inside a cylindrical reducer housing. While effective, this device requires fabricating a cylindrical reducer housing for insertion in the bung hole. The fabrication of such a housing requires many manufacturing steps which add to the expense and the time involved to make the completed lid. Also, because the reducer housing is inserted in the lid cover through a two inch threaded opening, this threaded interface provides an additional region to seal to prevent possible leaking.
3. Objects of the Invention
It is an object of this invention to have a valve assembly for a drum which is compact and which fits in a depression in the drum lid so that it does not extend above the height of the drum rim.
It is a further object of this invention to have a manually operated gas relief valve which can be safely operated to vent even explosive gases from a sealed drum, while providing a positive seal when such venting is prohibited.
It is a further object of this invention to provide a sealed drum with a simplified cover and with better cover integrity.
It is a further object of this invention to have a less expensive ventable drum cover by using a less costly reducer valve which can be simply made and quickly inserted into a drum cover.
It is a further object of this invention to have a valve assembly for a drum where the valve outlet is protectively positioned in a reservoir within the drum lid.
It is a further object of this invention to have a valve assembly where the valve outlet discharges into a reservoir which can be filled with water or other inert fluid to visually detect the flow of gas from the outlet as the gas bubbles into the reservoir.
These and further objects will become apparent as the description of the invention proceeds.